Contact-free interaction with an electronic device

Abstract

The present disclosure provides an electronic device configured to detect an object positioned at a distance. The electronic device includes a reference oscillator generating a reference signal having a reference frequency; and a first measurement oscillator coupled to a first antenna located at a first position of the electronic device. The first measurement oscillator generates a first measurement signal having a first measurement frequency corresponding to a distance of an object from the first antenna. The first antenna has a first antenna load corresponding to the distance of the object from the first antenna, and the first measurement frequency varies in dependence on the first antenna load. The electronic device also includes a comparator coupled to the reference oscillator and the first measurement oscillator which generates a comparator output including a difference between the reference frequency and the first measurement frequency which represents the distance of the object from the first antenna.

The invention claimed is: 
     
       1. An electronic device configured to detect contact-free interaction, comprising:
 a comparator; 
 a reference oscillator directly connected to the comparator and configured to generate a reference data signal having a reference frequency and output the reference data signal directly to the comparator; 
 a first antenna located at a first position of the electronic device, wherein the first antenna has a first antenna load having a reactance value based on inductive and capacitive elements of the first antenna, wherein the first antenna load varies in accordance with a location of an object within a sensitive region of the first antenna and a permittivity of the object; 
 a first measurement oscillator directly connected to the comparator and the first antenna, wherein the first measurement oscillator is configured to generate a first measurement data signal having a first measurement frequency corresponding to the first antenna load and output the first measurement data signal directly to the comparator, wherein the first antenna is tuned so that the first measurement frequency is substantially the same as the reference frequency when no object is within the sensitivity region of the first antenna and so that the first measurement frequency varies from the reference frequency by an amount that depends on the first antenna load; and 
 wherein the comparator receives the reference data signal directly from the reference oscillator and receives the first measurement data signal directly from the first measurement oscillator, wherein the comparator determines a difference between the reference frequency and the first measurement frequency, and outputs a first output data signal representing the determined difference which represents a distance of the object from the first antenna. 
 
     
     
       2. The electronic device of  claim 1 , wherein the reference frequency is a frequency within one of the industrial, scientific or medical (ISM) radio bands. 
     
     
       3. The electronic device of  claim 1 , wherein the comparator comprises a frequency mixer which receives the reference data signal and the first measurement data signal and outputs a difference signal having a difference frequency, wherein the difference frequency is equal to the difference between the reference frequency and the first measurement frequency. 
     
     
       4. The electronic device of  claim 3 , wherein the comparator converts the difference signal to a square-wave signal to determine the difference frequency. 
     
     
       5. The electronic device of  claim 4 , wherein the comparator comprises:
 a Schmitt-trigger circuit for converting the difference signal to the square-wave signal; and 
 a pulse counter for counting pulses of the square-wave signal during a predetermined time interval. 
 
     
     
       6. The electronic device of  claim 1 , further comprising:
 a second antenna located at a second position of the electronic device, wherein the second antenna has a second antenna load having a reactance value based on inductive and capacitive elements of the second antenna, wherein the second antenna load varies in accordance with a location of an object within a sensitive region of the second antenna and a permittivity of the object; 
 a second measurement oscillator directly connected to the comparator and the second antenna, wherein the second measurement oscillator is configured to generate a second measurement data signal having a second measurement frequency corresponding to the second antenna load and output the second measurement data signal directly to the comparator, wherein the second antenna is tuned so that the second measurement frequency is substantially the same as the reference frequency when no object is within the sensitivity region of the second antenna, and so that the second measurement frequency varies from the reference frequency by an amount that depends on the second antenna load; 
 a third antenna located at a third position of the electronic device, wherein the third antenna has a third antenna load having a reactance value based on inductive and capacitive elements of the third antenna, wherein the third antenna load varies in accordance with a location of an object within a sensitive region of the third antenna and a permittivity of the object; 
 a third measurement oscillator directly connected to the comparator and the third antenna, wherein the third measurement oscillator is configured to generate a third measurement data signal having a third measurement frequency corresponding to the third antenna load and output the third measurement data signal directly to the comparator, wherein the third antenna is tuned so that the third measurement frequency is substantially the same as the reference frequency when no object is within the sensitivity region of the third antenna, and so that the third measurement frequency varies from the reference frequency by an amount that depends on the third antenna load; 
 wherein the first, second and third antennas are positioned within a common plane and spaced apart from each other; 
 wherein the comparator receives the second measurement data signal and third measurement data signal directly from the second and third measurement oscillators, wherein the comparator determines a difference between the reference frequency and the second measurement frequency and outputs a second output signal representing the determined difference which represents a distance of the object from the second antenna, and wherein the comparator determines a difference between the reference frequency and the third measurement frequency and outputs a third output signal representing the determined difference which represents a distance of the object from the third antenna. 
 
     
     
       7. The electronic device of  claim 6 , wherein two of the first, second and third antennae are parallel to each other and the other of the first, second and third antenna is perpendicular to the other two antennae. 
     
     
       8. The electronic device of  claim 6 , further comprising a processor configured to determine from the first, second and third comparator outputs a relative location of the object based on the distance of the object to each of the first, second and third antenna. 
     
     
       9. The electronic device of  claim 8 , wherein the processor is further configured to:
 determine whether the location of the object moves over time; 
 when the location of the object moves over time, determine whether movement of the object matches an input model for a motion gesture to detect the motion gesture; and 
 perform an action associated with the detected motion gesture. 
 
     
     
       10. The electronic device of  claim 9 , wherein the action is dependent on a context in which the detected motion gesture was performed. 
     
     
       11. The electronic device of  claim 8 , wherein the electronic device is configured to detect a particular object or particular type of object is within the sensitivity region of the first antenna, wherein the processor is configured to determine the relative location of the object based on the distance of the object to each of the first, second and third antenna and the permittivity of the particular object or particular type of object. 
     
     
       12. The electronic device of  claim 6 , further comprising a rectangular display, wherein each of the first, second and third antennas is positioned along a side thereof. 
     
     
       13. The electronic device of  claim 6 , further comprising a rectangular keyboard, wherein each of the first, second and third antennas is positioned along a side thereof. 
     
     
       14. The electronic device of  claim 6 , further comprising a rectangular accessory device connected to the electronic device via a wired or wireless connection, wherein each of the first, second and third antennas is positioned along a side thereof. 
     
     
       15. The electronic device of  claim 6 , further comprising:
 a fourth antenna located at a fourth position of the electronic device, wherein the fourth antenna has a fourth antenna having a reactance value based on inductive and capacitive elements of the first antenna, wherein the first antenna load varies in accordance with a location of an object within a sensitive region of the fourth antenna and a permittivity of the object; 
 a fourth measurement oscillator directly connected to the comparator and the fourth antenna, wherein the fourth measurement oscillator is configured to generate a fourth measurement data signal having a fourth measurement frequency corresponding to the fourth antenna load and output the fourth measurement data signal directly to the comparator, wherein the fourth antenna is tuned so that the fourth measurement frequency is substantially the same as the reference frequency when no object is within the sensitivity region of the fourth antenna, and so that the fourth measurement frequency varies from the reference frequency by an amount that depends on the fourth antenna load; 
 wherein the fourth antenna is positioned in a different plane than the first, second and third antennas; 
 wherein the comparator receives the fourth measurement data signal directly from the fourth measurement oscillator, wherein the comparator determines a difference between the reference frequency and the fourth measurement frequency and outputs a fourth output signal representing the determined difference which represents a distance of the object from the fourth antenna. 
 
     
     
       16. The electronic device of  claim 15 , further comprising a processor configured to determine from the first, second, third and fourth comparator outputs an absolute location of the object based on the distance of the object to each of the first, second, third and fourth antenna. 
     
     
       17. The electronic device of  claim 16 , wherein the electronic device is configured to detect a particular object or particular type of object is within the sensitivity region of the first antenna, wherein the processor is configured to determine the absolute location of the object based on the distance of the object to each of the first, second, third and fourth antenna and the permittivity of the particular object or particular type of object. 
     
     
       18. The electronic device of  claim 1 , wherein the electronic device is configured to detect a particular object or particular type of object is within the sensitivity region of the first antenna. 
     
     
       19. The electronic device of  claim 18 , wherein the particular object or particular type of object comprises a hand or a stylus. 
     
     
       20. The electronic device of  claim 1 , wherein the reference oscillator is not connected to an antenna and the reference data signal is not transmitted via an antenna. 
     
     
       21. An electronic device, comprising:
 a filter; 
 a reference oscillator directly connected to the filter and configured to generate a reference data signal having the reference frequency and output the reference data signal directly to the filter; 
 a first antenna located at a first position of the electronic device, wherein the first antenna has a first antenna load having a reactance value based on inductive and capacitive elements of the first antenna, wherein the first antenna load varies in accordance with a location of an object within a sensitive region of the first antenna and a permittivity of the object within the sensitive region; 
 a first measurement oscillator directly connected to the filter and the first antenna to generate a first measurement data signal having a first measurement frequency corresponding to the first antenna load and output the first measurement data signal directly to the filter, wherein the first antenna is tuned so that the first measurement frequency is substantially the same as a reference frequency when no object is within the sensitivity region of the first antenna and so that the first measurement frequency varies from the reference frequency by an amount that depends on the first antenna load; and 
 wherein the filter receives the reference data signal directly from the reference oscillator and receives the first measurement data signal directly from the measurement oscillator, and outputs an output data signal representing a difference between the reference frequency and the first measurement frequency which represents a distance of the object from the first antenna. 
 
     
     
       22. The electronic device of  claim 21 , wherein the filter is any one of a notch filter tuned to block or attenuate a signal having a frequency equal to the reference frequency or a band stop filter tuned to allow a signal having a frequency equal to the reference frequency.